Functional lesions in dysphagia due to acute stroke: discordance between abnormal findings of bedside swallowing assessment and aspiration on videofluorography

Introduction

Bedside swallowing assessments are often used to assess dysphagia. However, in some patients, aspiration pneumonia occurs without any problems on bedside swallowing assessments and some patients do not suffer aspiration pneumonia despite abnormal results of bedside swallowing assessments in acute stroke. To detect the differences of lesions related to bedside swallowing assessment abnormality and aspiration, we investigated swallowing-related functional lesions in terms of cerebral blood flow in patients with dysphagia after stroke.

Methods

The study included 50 acute stroke patients who underwent bedside swallowing assessments and videofluorography as well as single-photon emission computed tomography (CT) at approximately the same time. Bedside swallowing assessments included repetitive saliva swallowing test and modified water swallowing test as dry and wet swallowing tasks. The presence or absence of aspiration was assessed using videofluorography. We divided patients into three subgroups based on the outcomes of the bedside swallowing assessments and presence or absence of aspiration. Statistical image analysis was performed using single-photon emission CT to determine their relationship with bedside swallowing assessments and videofluorography results.

Results

Twenty-seven (54.0 %) and 28 (56.0 %) patients had abnormal repetitive saliva swallowing test and modified water swallowing test results. Videofluorography indicated aspiration in 35 (70.0 %) patients. In comparing patients with and without abnormal results on each test, the groups with abnormal repetitive saliva swallowing test, abnormal modified water swallowing test, and aspiration demonstrated lower cerebral blood flow in the left precuneus, left insula, and anterior cingulate gyrus, respectively.

Conclusions

Based on the analysis of cerebral blood flow, functional lesions differed across abnormal repetitive saliva swallowing test and abnormal modified water swallowing test findings and aspiration on videofluorography, and each test may assess different functions among the many processes involved in swallowing.